1. Field of the Invention
This invention relates to hydrostatic support devices having a supporting surface wherein either the supporting surface or the surface of the object being supported, or both, are textured in order to provide a plurality of restrictions along the flow path of the supporting fluid.
2. Prior Art
Gas supported bearings have been employed in many devices. In U.S. Pat. No. 3,048,043 to J. N. Slater et al, gas supported bearings (see FIGS. 4 and 6 therein) in a gyroscope employ a series of inclined wedges separated by a series of plane portions or surfaces. Slater indicates that the wedges may be either on the thrusting surface or on the surface receiving the thrust.
In U.S. Pat. No. 3,195,963 to T. Anderson, a gas-lubricated, stepped bearing for near frictionless static and dynamic support of various objects is disclosed. The gas-lubricated bearing comprises a generally solid bearing seat having a recessed portion, the recessed portion defining a step at a common altitude on the periphery thereof. Anderson allows for a series of such steps. However when a series of steps are employed, the gap between the object supported and each successive step is smaller than the gap between the object supported and the preceding step. The steps serve to reduce vertical vibrations of the supported object upon the bearing seat. The steps cause the laminar flow of the gas to diverted from its previous path around the bearing. Anderson indicates that his invention can be used to support any circular cross section object. The steps are expressly distinguished from "grooves" or "zones" used, for example, to drain fluid or distribute pressure.
Further, in U.S. Pat. No. 3,439,962 to K. E. A. Gothberg, a reversible sliding gas bearing is disclosed comprising a stationary member and a rotatable member, both having confronting bearing surfaces, and intermediate member disposed between the sliding surface. The intermediate member also has sliding surfaces which confront and conform in shape to the sliding surfaces of the rotatable and stationary members. Spiral or helical grooves are provided on at least a portion of the surface of the intermediate member to pump supporting fluid into a support chamber when the rotatable member rotates either clockwise or counterclockwise.
For many hydrostatic bearing support systems the load is substantial thus necessitating high pressure fluid supplies. If simple clearance geometry is employed (i.e., the cross sectional dimensions of the flow path of the supporting fluid are constant or smoothly varying along the flow path), the result is a high outrush of supporting fluid through the bearing clearance. This consumes a great deal of supporting fluid, causes high viscous shear on the bearing and, possibly, impulse forces due to the exiting fluid impinging on the bearing. These effects are particularly distasteful for some applications such as the support of bearings in gyroscopes with gases. The high outflow entails high pumping power, or large storage bottles, with attendant payload and/or size penalties. The viscous shear and windage forces in such gyroscopes result in high torques and hence high attitude drift rates.
The devices disclosed by Slater and Gothberg do not describe means and methods for substantially reducing supporting fluid consumption rates in hydrostatic support devices. It would also be advantageous to reduce fluid consumption with a device which could be easily constructed and would be adaptable to virtually any supporting surface and/or the surface of the object being supported.
Further, although the device disclosed by Anderson does divert the kinetic energy of the laminar flow of the supporting fluid at each step, the successive decreases in the cross section of the flow path of the supporting fluid is not an efficient means or method to reduce the consumption rate of the support fluid. Further, Anderson discloses a device which is limited to supporting objects having circular cross sections and his disclosed structure can be used with bearing surfaces of only very particular shapes.